What is SuperFetch and its relation to svchost.exe - LocalSystemNetworkRestricted?
Superfetch is a service that was introduced with Vista and has been part of Windows ever since. It tries to speed up your computing experience by pre-loading parts of programs into memory with sometimes detrimental effects as you had to experience. It tries to determine which software you use and stores parts of it to the Windows folder.
Unfortunately, Superfetch doesn't always get it right which software you're going to use and can keep your hard drive busy for minutes after booting. I found it especially annoying since it kept on loading software I wasn't even going to use or that I had only used once. Since I use a plethora of different programs every day, Superfetch actually had a massive negative impact on my computer's performance with keeping the hard drive busy for 5-10 minutes after a fresh boot. This is the very reason I have been running Windows with deactivated Superfetch ever since it came out.
Additionally, since Superfetch uses memory for applications you might not even run, your free amount of memory will take a hit and might result in more swapping which adds just more wear to the hard drive.
Here's how to deactivate Superfetch:
Open up the Run prompt and enter Services.msc.
Find Superfetch in the list, right click it and stop the service.
Double-click on it and set its start up type to Disabled.
Once you reboot, Superfetch will stay inactive. Other culprits that may also slow your hard drive down can be automatically scheduled defrag sessions as well as Windows Search Indexer. You can deactivate the latter the same way as Superfetcher.
Svchost.exe is the executable that runs the service. You don't really have to mess with it after deactivating Superfetch. In fact, you should not touch it at all since it runs a lot of crucial Windows services.
You can check the Prefetch folder in the Windows directory to see which programs Superfetch prebuffered in your memory. You can safely delete them once Superfetch has been deactivated.